The present description relates to a dual-fuel engine, more specifically to an indicator for a vehicle having a dual fuel engine as its propelling power source.
When an internal combustion engine combusts fuel with air charged therein, it generates heat energy. The engine may be mounted on a vehicle, and may convert the heat energy to torque output to a drive-train to propel the vehicle. For example, in U.S. Patent Application Publication US2006/010823A1, a dual-fuel engine for an automotive vehicle is disclosed to selectively combust two different kinds of fuels, in this case, gaseous hydrogen and gasoline. Between the two different fuels, the amounts of heat energy generated from combustion of the same volume of stoichiometric mixtures are different. In a dual-fuel engine, the maximum mixture volume is constant, but maximum torque from the different kinds of fuel is different. For example, when the fuel is switched from gasoline to hydrogen, the engine output torque will decrease if, before the fuel switching, the engine outputs more torque from gasoline than the maximum torque from hydrogen.
Therefore, the vehicle propelling force may decrease when the fuel is switched. Then, the acceleration of the vehicle may be reduced, and the vehicle may even decelerate if the vehicle running resistance is greater for example in a high speed driving condition. As a result, when a rear vehicle follows a front vehicle with a dual-fuel engine, and the fuel supplied to the front vehicle is switched, both of the vehicle drivers may need to know about the possibility of reduced acceleration or deceleration of the front vehicle.
In the '823 publication, when the hydrogen is supplied to the engine, it is indicated to the vehicle driver. Thus, the driver is informed that the fuel is switched from gasoline to hydrogen. However, the driver cannot tell if there is the possibility of the reduced acceleration of the vehicle. Further, other drivers who may be following the driver, for example, have no way of recognizing the possibility of the reduced acceleration of the vehicle due to the fuel switch.